Tribological investigations on piston alloy based hybrid nano composite and GGG40 spheroidal cast iron under reciprocating dry sliding conditions

Abstract

GGG40 spheroidal cast iron is commonly used in engine blocks of passenger vehicles. However, it adds to the weight and wear of the engine block thereby costing us more energy. In this paper, fabrication and tribological investigations are carried out on dual particle sized hybrid nano composites to examine their potential to replace conventional GGG40 in engine applications. The SiC single and SiC-Si₃N₄+Gr dual sized ceramic reinforcements are introduced in piston alloy-Al6061 alloy through liquid metallurgy route. The tribological properties of GGG40 under reciprocating dry sliding conditions are also studied and compared to the fabricated composites. At 10 N, GGG40 shows 0.6714 coefficient of friction while it is 0.424 for the hybrid composite (decreased by 51.74%). At 25 N, coefficient of friction for hybrid composites comes out to be 0.4732 which is 26.11% less than GGG40 for which it is 0.5955. Wear rate for hybrid composites at 10 N is 4.71 × 10^–6 mm³/Nm which is 62.71% less than the wear rate of GGG40 which is 20.2 × 10^–6 mm³/Nm. At 25 N, the fabricated composites show wear rate equal to 9.41 × 10^–6 mm³/Nm which is 16.5% less than GGG40 which shows 11.7 × 10^–6 mm³/Nm wear rate. Micro sized SiC with nano sized Si₃N₄ generate a compact and smooth tribo film on the surface of base alloy with graphite further adding to the durability of the tribo film. The fabricated composites can be the good replacement of conventional GGG40 in automobile applications.